Our K protocol is adjusted in the orders based on creatinine levels. I think you need to take in account all facts per individual patients before given electrolyte replacement. Magnesium does not have a protocol on our unit for our s/p CABG. The patients under the care of our critical docs have replacement criteria for everything. I feel that if you are ever questioning giving a dose, call the MD and ask for parameters related to creatinine level. As far as TPN goes call the pharmacist who mixes and ask about replacement. There is no wrong answer. If the patient is on diuretics than K may need to be replaced. We check one hour after infusion is complete. For HD patients, the electrolytes are usually replaced by HD Rn and MD. Hope this helps... Ask your coworkers, it is always good to get a consensus.